As use of cloud computing spreads, demand for storage systems capable of storing large amounts of data and processing input and output of data at a high speed increases. Further, as demand for managing big data becomes more significant, the workloads on the storage systems become more significant. To meet such demands, a storage system including a plurality of storage nodes that are communicably networked is proposed. However, in such a storage system, delay of a process by one storage node may negatively affect performance of the entire storage system.